The present invention relates to an intermediate transfer member, a producing method for the intermediate transfer member and an image forming method.
Electrophotographic image forming apparatus is recently spread into a field of printing called as convenience printing additionally to the field of copy machine and printer for office use, and is noted because it has a merit that several thousands sheets of print can be printed for a shorten time without plate making.
In one of the electrophotographic image forming methods, an image is formed by a process in which a toner image formed on a photoreceptor is primarily transferred onto an intermediate transfer member and then the transferred toner image is secondarily transferred onto a recording medium.
Such the image forming method has a merit of that many sheets of print can be made at high speed and improvement in the intermediate transfer member is continued for obtaining good transferring ability and high durability. The currently used intermediate transfer belt employs a thermoplastic resin such as polycarbonate and polyphenylene sulfide, or a resin formed in a cylindrical form by heating reaction such as polyimide and polyamideimide. In response to the recent requirements for smaller toner diameter, higher process speed and more compact machine, it has become necessary to meet increasingly stringent requirements for image quality. Among others, problems have been found in“dropout”—removal of toner from the center of letters and line drawings—and “transfer failure”—uneven density of a solid image.
For these problems in the transferring ability, for example, it is tried to provide a surface potential detecting device for detecting the potential on the back surface of the intermediate transfer member at a point being between the primary transfer position and the secondary transfer position, cf. Tokkai (Japanese Patent Application Laid-Open Publication) No. 2002-365937 for example. When a device to detect the surface potential is installed to prevent secondary transfer performances from deteriorating, however, the image forming apparatus becomes complicated and the cost increase results. This attempt according to the conventional art has failed to solve the problem related to lack of uniformity including a partial variation of the belt characteristics.
Another approach known in the conventional art is found in the belt characterized by lubricating agent coated on the surface of an intermediate transfer belt for improving release characteristics (cf. Tokkai 2005-234589). However, when the belt coated with lubricating agent is used for a long time, a crack occurs to the surface layer, the lubricating agent coated on the surface layer is separated or cleaning failure is caused by the vibration of the blade, with the result that durability is insufficient, according to this conventional approach.